National Instruments cFP-RTD-122 User's Manual
Contents
1. channel independently so you can connect different types of RTDs to each channel Sy Note You must configure each channel of the c FP RTD 122 for the RTD type connected to it The module does not automatically recognize RTD types RTD Types RTD types are specified by material composition nominal resistance at 0 C and TCR The c FP RTD 122 can directly measure the temperature of platinum RTDs of either 100 or 1 000 Q nominal resistance These RTDs are commonly referred to as PT100 or PT1000 RTDs respectively Different types of platinum RTDs have different TCRs The c FP RTD 122 supports the following TCRs 3 750 3 851 3 911 3 916 3 920 and 3 928 mQ2 Q C The most common TCR for RTDs is 3 851 mQ Q C It is defined in international standards such as IEC 751 DIN 43760 BS 1904 and ASTM E1137 The TCR of 3 928 mQ Q C is used in the reference function for platinum thermometers in the International Temperature Scale of 1990 ITS 90 for high accuracy metrology applications Unfortunately not all TCR values are as well defined by standards organizations and the behavior of RTDs with the same TCR value may vary from vendor to vendor The variations are usually small and the built in linearization algorithms of the c FP RTD 122 are appropriate for nearly all applications National Instruments Corp 7 FP RTD 122 and cFP RTD 122 The c FP RTD 122 uses a linearization curve known as the Callendar Van Dusen equation to2. measure the temperature of RTDs The equation is as follows Temperatures below 0 C Rr R 1 AxT B xT C xT x T 100 C Temperatures above 0 C Rr R 1 AxT BxT T temperature in C Rr RTD resistance at temperature T Ro RTD nominal resistance at 0 C A B C are coefficients given in Table 2 Table 2 lists the coefficients used in this equation for each of the TCR values that the c FP RTD 122 supports If you have a nonstandard RTD that does not match one of these linearization curves measure the resistance with the c FP RTD 122 and convert the resistance to temperature in the manner suggested by the RTD vendor Table 2 Callendar Van Dusen Coefficients Used by the c FP RTD 122 TCR A B C mO Q C CC C CO 3 750 3 81 x 103 6 02 x 10 7 6 0 X 10 2 3 851 3 9083 x 1073 5 775 X 1077 4 183 x 10 2 3 911 3 9692 x 1073 5 8495 x 10 7 4 233 x 10 2 3 9169 3 9739 x 103 5 870 X 10 7 4 4 X 10 2 3 920 3 9787 x 10 5 8686 X 10 7 4 167 x 10 2 3 928f 3 9888 x 103 5 915 X 1077 3 85 X 10 12 Three Wire Compensation of Lead Resistance Errors The c FP RTD 122 uses a three wire compensation technique to compensate for the lead resistances The SENSE lead measures the resistance of the return COM lead If the EX lead has the same resistance as the COM lead the c FP RTD 122 corrects for the FP RTD 122 and cFP RTD 122 ni com effects of th
3. that prevents accidental or unauthorized access to wiring that carries hazardous voltages FP RTD 122 and cFP RTD 122 10 ni com e Operate the c FP RTD 122 only at or below Pollution Degree 2 Pollution Degree 2 means that only nonconductive pollution occurs in most cases Occasionally however a temporary conductivity caused by condensation must be expected e Refer to the FieldPoint product label for regulatory certification under hazardous location standards If the FieldPoint product is not certified for operation in hazardous locations do not operate it in an explosive atmosphere or where there may be flammable gases or fumes Specifications These specifications are typical for the range 40 to 70 C unless otherwise noted Gain error is calculated as a percentage of input signal value Input Characteristics Number of channels ecee 8 ADC resolution ieee 16 bits Type of ADC eee eeseeeeteeeeeeees Delta sigma Input signal ranges software selectable by channel TeMperature cece 73 to 1123 K 200 to 850 C 328 to 1562 F Resistance m ea eteni 0 to 400 Q or 0 to 4 000 Q Temperature accuracy includes 5 matched 0 5 Q lead wires 10 m of 22 AWG copper Error 15 to 35 C 40 to 70 C Measured Value Typical Maximum Typical Maximum 200 to 150 C 0 15 0 30 0 40 1 6 150 to 850 C 0 25 0 50 0 90 3 0 Resolution vesien haniai 0 016 C
4. FieldPoint Operating Instructions FP RTD 122 and cFP RTD 122 Eight Channel Three Wire RTD and Resistance Input Modules These operating instructions describe how to install and use the National Instruments FP RTD 122 and cFP RTD 122 three wire RTD and resistance input modules referred to inclusively as the c FP RTD 122 For details on configuring and accessing the c FP RTD 122 over a network refer to the user manual for the FieldPoint network module you are using Features The c FP RTD 122 is a FieldPoint RTD and resistance input module with the following features Inputs for 100 and 1 000 Q platinum RTDs resistance temperature detectors e Built in linearization for six TCR temperature coefficient of resistance or alpha values of RTDs e Direct resistance measurements in 400 and 4 000 Q ranges True three wire compensation e 16 bit resolution e Filtering against 50 and 60 Hz noise e Hot swappable e 2 300 V ms transient overvoltage protection e 40 to 70 C operation FieldPoint National Instruments NI and ni com are trademarks of National Instruments Corporation Product and company names mentioned herein are trademarks or trade names of their respective companies For patents covering National Instruments products refer to the appropriate location Help Patents in your software the patents txt file on your CD orni com patents 323348B 01 April 2003 Ww NATIONAL 2002 2003 N
5. Resistance accuracy Offset error 400 Q range TES o o a a C cet 0 03 Q typ 0 08 Q max 40 to 70 CC 0 08 Q typ 0 4 Q max National Instruments Corp 11 FP RTD 122 and cFP RTD 122 Offset error 4 000 Q range IS Coes as Ca em eer ee 0 2 Q typ 0 7 Q max 40 to 70 Coie cece eceteees 0 8 Q typ 4 0 Q max Gain error 15 t0 35 C Sivtenieesticesneelst 0 01 typ 0 02 max 40 to 70 Coes 0 07 typ 0 1 max Resolution 400 Q range eee 0 0061 Q 4 000 Q range 0 061 Q Excitation Current eee 135 ms pulses of 0 25 mA every 1 080 ms Input noise 0 eee eeeeeteeeeeeeeeneenees 1 bit peak to peak Input bandwidth eee 3 Hz Update rate Each channel is updated every 1 08 s Physical Characteristics Indicator S z 2 ccss cio tenes Green POWER and READY indicators Weight FP RTD 122 nenaon 140 g 4 8 oz CFP RTD 122 reete eeii 110 g 3 7 oz Power Requirements Power from network module 350 mW Isolation Voltage Channel to channel isolation No isolation between channels Transient overvoltage seeeeeeee 2 300 Vims Environmental FieldPoint modules are intended for indoor use only For outdoor use FieldPoint modules must be mounted inside a sealed enclosure Operating temperature 40 to 70 C Storage temperature 55 to 85 C HUMIC peenaa 10 to 90 RH noncondensing FP RTD 122 and cFP RTD 122 12 ni com Maximum altitude ccceeeeeeee 2 000 m at high
6. age Directive safety 73 23 EEC Electromagnetic Compatibility Directive EMC nsss 89 336 EEC 3 Note Refer to the Declaration of Conformity DoC for this product for any additional regulatory compliance information To obtain the DoC for this product click Declarations of Conformity Information at ni com hardref nsf Mechanical Dimensions Figure 7 shows the mechanical dimensions of the FP RTD 122 installed on a terminal base If you are using the cFP RTD 122 refer to the Compact FieldPoint controller user manual for the dimensions and cabling clearance requirements of the Compact FieldPoint system suupuing 107 19 mm gt i s lt 4 22 in 109 5 mm 4 31 in Eee re PJ af 4 91 44 mm 3 60 in SS Figure 7 FP RTD 122 Mechanical Dimensions Where to Go for Support For more information about setting up the FieldPoint system refer to these National Instruments documents e FieldPoint network module user manual e Other FieldPoint I O module operating instructions e FieldPoint terminal base and connector block operating instructions FP RTD 122 and cFP RTD 122 14 ni com Go to ni com support for the most current manuals examples and troubleshooting information For telephone support in the United States create your service request at ni com ask and follow the calling instructions or dial 512 795 8248 For telephone suppor
7. ational Instruments Corp All rights reserved gt INSTRUMENTS Installing the FP RTD 122 The FP RTD 122 mounts on a FieldPoint terminal base FP TB x which provides operating power to the module Installing the FP RTD 122 onto a powered terminal base does not disrupt the operation of the bank To install the FP RTD 122 refer to Figure 1 and complete the following steps 1 Slide the terminal base key to either position X used for any module or position 1 used for the FP RTD 122 module 2 Align the FP RTD 122 alignment slots with the guide rails on the terminal base 3 Press firmly to seat the FP RTD 122 on the terminal base When the module is firmly seated the terminal base latch locks it into place 1 1 0 Module 4 Key 2 Terminal Base 5 Latch 3 Alignment Slot 6 Guide Rails Figure 1 Installing the FP RTD 122 Installing the cFP RTD 122 The cFP RTD 122 mounts on a Compact FieldPoint backplane cFP BP x which provides operating power to the module Installing the cFP RTD 122 onto a powered backplane does not disrupt the operation of the bank FP RTD 122 and cFP RTD 122 2 ni com To install the cFP RTD 122 refer to Figure 2 and complete the following steps 1 Align the captive screws on the cFP RTD 122 with the holes on the backplane The alignment keys on the cFP RTD 122 prevent backward insertion 2 Press firmly to seat the cFP RTD 122 on the backplane Using a number 2 Phillips
8. e leads The only residual errors are those caused by mismatching the EX and COM leads Most RTDs have lead resistances within 5 of each other so the compensation of the c FP RTD 122 corrects for 95 or more of the errors introduced by lead resistances This is a more accurate method than the typical bridge completion methods described in many reference books The bridge methods not only have the same sensitivity to lead resistance mismatch but also are effective only for temperatures very near those at which the bridge is balanced usually 0 C The temperature measurement accuracy specifications for the c FP RTD 122 at the end of these instructions include the effects of a typical application using 10 m of 22 gauge copper wire approximately 0 5 Q per lead with 5 mismatch in the lead resistances If you are using leads with greater resistances the additional errors are approximately 3 C per Q of mismatch in the lead resistances for 100 Q RTDs and 0 3 C per Q of mismatch in the lead resistance for 1 000 Q RTDs For example for 2 Q leads matched to 5 of each other the lead resistance mismatch is 5 x2 Q 0 1 Q which would cause 0 3 C of error in measurements of a 100 Q RTD If you are using the c FP RTD 122 with two wire RTDs the errors due to lead resistances are much greater because three wire compensation is not used With two wire RTDs the additional errors are approximately 3 C per Q of the sum of the lead resistanc
9. er altitudes the isolation voltage ratings must be lowered Pollution Degree scce 2 Shock and Vibration These specifications apply only to the cFP RTD 122 NI recommends Compact FieldPoint if your application is subject to shock and vibration Operating vibration random IEC 60068 2 64 eee eeeeeeeeeee 10 500 Hz 5 gims Operating vibration sinusoidal IEC 60068 2 6 eee eeeeeeeteeeees 10 500 Hz 5 g Operating shock IEC 60068 2 27 cccceesesteeseeeeeeeee 50 g 3 ms half sine 18 shocks at 6 orientations 30 g 11 ms half sine 18 shocks at 6 orientations Safety This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement control and laboratory use e IEC 61010 1 EN 61010 1 e UL3121 1 UL 61010C 1 e CAN CSA C22 2 No 1010 1 For UL hazardous location and other safety certifications refer to the product label or to ni com Electromagnetic Compatibility CE C Tick and FCC Part 15 Class A Compliant EMisSiONS c cccccccesssceesseessseeessees EN 55011 Class A at 10 m FCC Part 15A above 1 GHz Tm Mity iiinis EN 61326 1997 A2 2001 Table 1 3 Note For EMC compliance operate this device with shielded cabling National Instruments Corp 13 FP RTD 122 and cFP RTD 122 CE Compliance This product meets the essential requirements of applicable European Directives as amended for CE Marking as follows Low Volt
10. er module communication bus The isolation is provided by the module which has optical and galvanic isolation barriers designed and tested to protect against transient fault voltages of up to 2 300 Vins Follow these guidelines to ensure a safe total system The c FP RTD 122 has a safety isolation barrier between the T O channels and the inter module communication bus There is no isolation between channels unless otherwise noted If any of the channels on a module are wired at a hazardous potential make sure that all other devices or circuits connected to that module are properly insulated from human contact e Do not share the external supply voltages the V and C terminals with other devices including other FieldPoint devices unless those devices are isolated from human contact e For Compact FieldPoint you must connect the protective earth PE ground terminal on the cFP BP x backplane to the system safety ground The backplane PE ground terminal has the following symbol stamped beside it Connect the backplane PE ground terminal to the system safety ground using 14 AWG 1 6 mm wire with a ring lug Use the 5 16 in panhead screw shipped with the backplane to secure the ring lug to the backplane PE ground terminal e As with any hazardous voltage wiring make sure that all wiring and connections meet applicable electrical codes and commonsense practices Mount terminal bases and backplanes in an area position or cabinet
11. es for 100 Q RTDs and 0 3 C per Q of the sum of lead resistances for 1 000 Q RTDs For example a 1 000 Q two wire RTD with 2 Q leads has a total lead resistance of 4 Q 2 Q per lead which causes 1 2 C of error Status Indicators The c FP RTD 122 has two green status LEDs POWER and READY After you insert the c FP RTD 122 into a terminal base or backplane and apply power to the connected network module the green POWER indicator lights and the c FP RTD 122 informs the network module of its presence When the network module recognizes the c FP RTD 122 it sends initial configuration information to the c FP RTD 122 After the c FP AI 111 receives this initial information the green READY indicator lights and the module is in normal operating mode National Instruments Corp 9 FP RTD 122 and cFP RTD 122 Upgrading the FieldPoint Firmware You may need to upgrade the FieldPoint firmware when you add new I O modules to the FieldPoint system For information on determining which firmware you need and how to upgrade your firmware go toni com info and enter fpmatrix Isolation and Safety Guidelines Caution Read the following information before attempting to connect the c FP RTD 122 to any circuits that may contain hazardous voltages This section describes the isolation of the c FP RTD 122 and its compliance with international safety standards The field wiring connections are isolated from the backplane and the int
12. rrent out of the EX terminal The excitation current returns through the COM terminal The SENSE terminal measures resistance and compensates for lead resistance errors Each channel is filtered then sampled by a 16 bit analog to digital converter FP RTD 122 and cFP RTD 122 4 ni com 5 RTD i Pulsed Input 16 bit Circuitry ADC SENSE i COM i c FP RTD 122 Figure 3 c FP RTD 122 Input Circuitry Taking Measurements from Three Wire RTDs Three wire RTDs often have a wire of one color usually white sometimes red for positive excitation and two wires of another color usually red sometimes black Connect the positive excitation wire to the EX terminal of the module and connect the other two wires to the SENSE and COM terminals 3 wire RTD c FP RTD 122 Figure 4 Three Wire RTD Connections on One Channel Taking Measurements from Four Wire RTDs For the best accuracy use the NI c FP RTD 124 for input from four wire RTDs Otherwise leave any one of the RTD wires unconnected and connect the remaining three as you would for a three wire RTD Refer to Figure 5 National Instruments Corp 5 FP RTD 122 and cFP RTD 122 Leave this wire i unconnected i i 1 4 wire RTD SENSE COM cJFP RTD 122 Figure 5 Four Wire RTD Connections on One Channel Taking Measurements from Two Wire RTDs Connect either wire of a
13. screwdriver with a shank of at least 64 mm 2 5 in length tighten the captive screws to 1 1 N m 101b in of torque The nylon coating on the screws prevents them from loosening cFP RTD 122 4 Screw Holes Captive Screws 5 cFP Backplane 3 cFP Controller Module to Figure 2 Installing the cFP RTD 122 National Instruments Corp 3 FP RTD 122 and cFP RTD 122 Wiring the c FP RTD 122 The FP TB x terminal bases have connections for each of the eight input channels on the FP RTD 122 The cFP CB x connector blocks provide the same connections for the cFP RTD 122 Table 1 lists the terminal assignments for the signals associated with each channel The terminal assignments are the same for the FP TB x terminal bases and the cFP CB x connector blocks Table 1 Terminal Assignments Terminal Numbers Channel EX SENSE COM 0 1 2 18 1 3 4 20 2 5 6 22 3 7 8 24 4 9 10 26 5 11 12 28 6 13 14 30 7 15 16 32 If you are using shielded wiring you can reduce input signal noise by connecting one end of the shield to the COM terminal Do not connect the shield to any of the wires at the signal end Taking RTD Measurements with the c FP RTD 122 The c FP RTD 122 has eight input channels All eight channels share a common ground reference that is isolated from other modules in the FieldPoint system Each channel pulses a 0 25 mA excitation cu
14. t outside the United States contact your local branch office Australia 61 2 9672 8846 Austria 43 0 662 45 79 90 0 Belgium 32 0 2 757 00 20 Brazil 55 11 3262 3599 Canada Calgary 403 274 9391 Canada Montreal 514 288 5722 Canada Ottawa 613 233 5949 Canada Qu bec 514 694 8521 Canada Toronto 905 785 0085 Canada Vancouver 514 685 7530 China 86 21 6555 7838 Czech Republic 420 2 2423 5774 Denmark 45 45 76 26 00 Finland 385 0 9 725 725 11 France 33 0 1 48 14 24 24 Germany 49 0 89 741 31 30 Greece 30 2 10 42 96 427 Hong Kong 2645 3186 India 91 80 51190000 Israel 972 0 3 6393737 Italy 39 02 413091 Japan 81 3 5472 2970 Korea 82 02 3451 3400 Malaysia 603 9059 6711 Mexico 001 800 010 0793 Netherlands 31 0 348 433 466 New Zealand 64 09 914 0488 Norway 47 0 32 27 73 00 Poland 48 0 22 3390 150 Portugal 351 210 311 210 Russia 7 095 238 7139 Singapore 65 6 226 5886 Slovenia 386 3 425 4200 South Africa 27 0 11 805 8197 Spain 34 91 640 0085 Sweden 46 0 8 587 895 00 Switzerland 41 56 200 51 51 Taiwan 886 2 2528 7227 United Kingdom 44 0 1635 523545 National Instruments Corp 15 FP RTD 122 and cFP RTD 122
15. two wire RTD to the EX terminal and the other wire to the COM terminal and connect a short jumper wire between the COM and SENSE terminals EX 2 wire RTD i SENSE Short Jumper Wire COM f c FP RTD 122 Figure 6 Two Wire RTD Connections on One Channel Measuring Resistance Directly You can use the c FP RTD 122 to measure resistance in ohms In this way you can take measurements from RTDs of types that the c FP RTD 122 does not directly support such as 120 Q nickel RTDs and from resistive devices other than RTDs You can choose one of two resistance ranges 0 400 and 0 4 000 Q Resistance values outside the range you select including open circuits result in an Out of range error for the affected channels The c FP RTD 122 ignores any configuration of RTD type for channels with resistance ranges selected FP RTD 122 and cFP RTD 122 6 ni com Converting Resistance Measurements to Temperature Measurements The c FP RTD 122 has built in linearization algorithms for platinum RTDs of either 100 or 1 000 Q nominal resistance and for six TCR or alpha a values The TCR is the average temperature coefficient of resistance of an RTD from 0 to 100 C This document specifies TCR in units of mQ Q C The c FP RTD 122 linearizes resistance values and returns readings in units of temperature The available ranges are 73 to 1 123 K 200 to 850 C and 328 to 1 562 F You can configure each
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